Gastrostomy and jejunostomy tubes are used to deliver nutritional products to the gastrointestinal tract of a patient. Gastrostomy tubes are positioned such that a nutritional product is delivered percutaneously from an external source directly to the patient's stomach. Jejunostomy tubes are positioned such that the nutritional product is delivered to the patient's small bowel. Gastrostomy and jejunostomy tubes are referred to collectively herein as "feeding tubes."
In one method for placing a feeding tube in a patient, an endoscope is passed down the patient's esophagus in order to view the esophagus and to ensure that there are no obstructions or lesions in the esophagus that will inhibit or preclude the passage of the tube through the esophagus. The endoscope also may be used to examine the interior of the stomach and/or the small bowel to select an entry point for the feeding tube. Next, the doctor transilluminates the entry point by directing light outwardly from endoscope such that the light shines through the patient's abdominal wall, thereby identifying the location at which the feeding tube is to enter the gastrointestinal tract. The doctor then makes an incision through the abdominal wall into the gastrointestinal tract and passes a first end of a guidewire percutaneously into the stomach through the resulting incision. Alternatively, the doctor may insert a hollow needle through the abdominal wall and into the stomach, and then pass a first end of a guidewire percutaneously into the stomach through the hollow needle. The first end of the guidewire is grasped with a grasping tool which may be associated with the endoscope, and the grasping tool and the guidewire are drawn outwardly from the patient's stomach and esophagus and through the patient's mouth. Upon completing this step of the procedure, a second end of the guidewire remains external to the patient's abdominal wall while the first end of the guidewire extends through the patient's mouth.
In one technique for feeding tube placement, the first end of the guidewire is attached to a feeding tube. By pulling on the second end of the guidewire, the feeding tube is pulled through the patient's mouth and esophagus, and then into the stomach. Further pulling of the second end of the guidewire causes the feeding tube to exit the stomach through the abdominal wall. Passage of the feeding tube through the abdominal wall may be facilitated by placing a dilating, conical tip on the leading end of the feeding tube. The feeding tube then is pulled through the abdominal wall until a retaining member mounted on the second end of the feeding tube engages the interior of the stomach. This technique is referred to as a "pull" technique.
In an alternative technique for feeding tube placement, the feeding tube is placed over the guidewire and is pushed along the guidewire such that the feeding tube passes through the patient's mouth, esophagus, and stomach until the first end of the feeding tube exits through the abdominal wall. The feeding tube is then drawn through abdominal wall until the retaining member on the second end of the feeding tube engages the interior of the stomach. This technique is referred to as a "push" or an "over-the-wire" technique.
Feeding tubes also can be placed by inserting the feeding tube through a stoma tract formed through the patient's abdominal wall. Insertion of the internal end of the feeding tube typically is facilitated by using dilators in order to provide an adequate tract through which the feeding tube and the retaining member can be inserted. This technique is preferably used to place feeding tubes through mature stoma tracts, but may be used when tumors or lesions within the patient's esophagus preclude passage of the feeding tube through the esophagus.
A variety of retaining members are used to prevent the feeding tube from exiting through the patient's abdominal wall after it has been placed. For example, a variety of shapes of fillable "balloon" retaining members are commercially available. These retaining members are fluidly connected to a filling channel. The filling channel can be formed integrally with the feeding tube, i.e., formed within or on an exterior surface of the feeding tube, or can be a separate element. The filling channel extends to a position outside of the patient and typically terminates at a valve. In order to fill the retaining member, a fluid, e.g., air, water, glycerine, or saline, is injected through the valve and into the retaining member. In order to empty the retaining member, the fluid is withdrawn from the retaining member via the valve. A syringe typically is used in order to fill and empty the retaining member.
The valve associated with known fillable retaining members is readily accessible at a point exterior to the patient. As a result of the accessibility of these valves, there is a possibility of an inadvertent release of pressure from the retaining member, thus making it possible to inadvertently remove the feeding tube from the patient. In addition, due to the accessibility of the valve, medical professionals sometimes overutilize the valve, resulting in the overfilling, and in some cases the bursting, of the fillable retaining member.
Fillable retaining members are typically constructed of silicone or latex rubber which tends to degrade in the presence of gastric juices over relatively extended periods of time. In addition, it has been found that silicone retaining members, when filled with water, may lose volume over time due to hydraulic and osmotic pressures across the wall of the retaining member.